Welt tension apparatus

ABSTRACT

The apparatus controls the tension applied to a welt being fed to a needle of a sewing machine. A welt guide arm, having an opening at a free end thereof through which the welt is passed, is secured to a base supporting the sewing machine at a position in proximity to the needle of the machine. A welt tension lever is pivotably secured to the guide arm. This lever has a free end in juxtaposition to the opening in the free end of the guide arm. A force applying device is coupled to the lever to move the free end of the lever into contact with a welt. The force applied by the force applying device is controllable so that the pressure applied to the welt by the free end of the lever is controlled to a prescribed amount. In such a manner, the tension on the welt delivered to the needle of the machine is substantially uniform over extended time intervals.

United States Patent [451 Oct. 24, 1972 Gawel [54] WELT TENSION APPARATUS [72] Inventor: Walter J. Gawel, Warren, Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: May 24, 1971 [21] Appl. No.: 146,340

[52] US. Cl ..112/152, 112/52 [51] Int. Cl. ..D05b 35/06 [58] Field of Search ..112/136, l39,141,142,143, 112/152,153, 150, 50, 51, 52, DIG. 2, DIG. 3

[56] References Cited UNlTED STATES PATENTS 1,899,399 2/1933 Sanborn ..112/152 2,779,299 1/1957 Randall ..112/52 2,907,289 10/1959 Fernandez ..112/152 X 3,515,081 6/1970 Miller ..112/152 X Primary ExaminerH. Hampton Hunter Att0rneyJohn R. Faulkner and William E. Johnson [57] ABSTRACT The apparatus controls the tension applied to a welt being fed to a needle of a sewing machine. A welt guide arm, having an opening at a free end thereof through which the welt is passed, is secured to a base supporting the sewing machine at a position in proximity to the needle of the machine. A welt tension lever is pivotably secured to the guide arm. This lever has a free end in juxtaposition to the opening in the free end of the guide arm. A force applying device is coupled to the lever to move the free end of the lever into contact with a welt. The force applied by the force applying device is controllable so that the pressure applied to the welt by the free end of the lever is controlled to a prescribed amount. In such a manner, the tension on the welt delivered to the needle of the machine is substantially uniform over extended time intervals.

10 Claims, 5 Drawing Figures PATENTEDUBT24 m2 9.999.909

SHEET 2 0F 2 WELT TENSION APPARATUS BACKGROUND OF THE INVENTION In many sewing styles, especially automotive soft trim and furniture applications, a vinyl welt is sewn into a joined seam of two patterns to achieve a finished seam appearance. The most economical method of performing this operation is to join the patterns and the welt simultaneously. The welt is fed continuously from a spool to a needle of a sewing machine at which place it is positioned between the two patterns.

The seam appearance after the joining of the patterns and the welt is a function of the tension applied to the welt prior to its joining to the patterns. More particularly, seam appearance is adversely effected by inconsistent tension on the welt during the sewing operation. The patterns and the welt form a misaligned and/or puckered seam depending upon the variability of the tension on the welt at the time of its joining to the patterns.

The prior art has taught many devices for controlling the tension on the welt prior to and during its joining to patterns. Such prior art devices are generally in the form of a pair of scissor members which apply a gripping force to a welt as it passes through free ends of the members. The gripping force is generally achieved by applying a spring force to the scissor members.

Difficulties are encountered with such prior art devices in many instances. For example, if the cross sectional thickness of the welt material changes slightly, the scissor members apply a greater tension to the welt during the passage of the thicker material through the free ends of the members. This increased tension on the welt results in an improper joining of the welt to the patterns and a finished seam of poor quality. Such spring loaded, welt tensioning devices are also found to be ineffective from the standpoint that the spring pressure changes over a period of time. More particularly, as the springs employed in the tensioning device are used over an extended time interval, the force applied to the scissor members gripping the welt changes. As the change in the gripping pressure on the welt occurs, the quality of the finished seam achieved in sewing the patterns to the welt declines.

It is the principal undertaking of this invention to provide a welt tensioning apparatus which controls uniformly the tension applied to a welt over a prolonged period of time. in accomplishing this desired undertaking, the apparatus of this invention is so designed that varying sizes of a welt from a nominal size does not cause substantial changes in the tension on the welt during the joining operation. In particular, a thickening of the welt from a nominal size does not cause an increased tension on the welt nor does a decrease in the thickness cause a decrease in the tension on the welt.

SUMMARY OF THE INVENTION This invention relates to an apparatus for controlling the tension applied to a welt and, more particularly, to an apparatus for controlling the tension applied to a welt being fed to a needle of a sewing machine. The tension on the welt may be controlled to any desired value and the tension may be maintained substantially uniform over an extended time interval.

The apparatus of this invention includes a base for supporting a sewing machine which has a sewing needie. A welt guide arm is provided which has an opening therein at a free end thereof, the opening conforming to the cross sectional shape of the welt. The welt is passed through this opening in its travel to the sewing needle. Mounting structure is provided for securing the welt guide arm to the base in a position so that the free end of the arm is positioned in proximity to the needle of the sewing machine. A welt tension lever is pivotably secured to the welt guide arm. The lever has a free end for applying a pressure on the welt at a position in juxtaposition to the opening in the free end of the arm. The free end of the lever applies tension on the welt by forcing a slight misalignment in the welt between its passage through the opening of the arm and its passage by the free end of the lever. A fluid pressure controlled force applying device is coupled to the welt tensional lever for applying a force on the lever to control the actual amount of pressure applied by the free end of the lever on the welt. A fluid pressure regulating device is employed for varying the force applied by the fluid pressure controlled force applying device on the welt tension lever. In this manner, the pressure applied to the welt by the levers free end is controlled to a prescribed amount and the tension on the welt delivered to the needle of the sewing machine is substantially uniform over extended time intervals.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a prior art apparatus utilized for tensioning a welt during a welt sewing operation.

FIG. 2 is a perspective view of a welt sewn between a pair of patterns.

FIG. 3 is an elevation view of a sewing machine in which a welt tensioning apparatus, formed in accordance with the teachings of this invention, is installed.

FIG. 4 is a perspective view of the welt tensioning apparatus of FIG. 3, the Figure showing, in greater detail, structural aspects of the apparatus.

FIG. 5 is an exploded, perspective view showing selected portions of the welt tensioning apparatus of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 there is shown a prior art welt tensioning apparatus, generally designated by the numeral 10. The apparatus applies tension or drag on a welt l l which is being sewn between a pair of patterns 12-12. As is indicated best in FIG. 2, once the welt is sewn between the patterns, the patterns are folded back so that the joined edges of the patterns have a finished look. The joining of the patterns to the welt is accomplished by a sewing needle 13 operated by a standard, industrial sewing machine.

In the prior art welt tensioning apparatus 10, a pair of scissor members 14 are employed. These scissor members have their free ends 16 formed so as to conform to the cross section of the welt 11 when the welt is enclosed thereby. By applying a spring force on the scissor members, the free ends thereof grip the welt l1 and apply a drag thereon. This drag or tension is applied to the welt in the binding of the welt to the patterns 12 in hopes of achieving a good looking, finished seam. Difficulties are encountered with this prior art type of structure as has been described in the background section of this specification.

The structure of this invention has been designed to apply a constant, but controllable, tension to a welt during a sewing operation. The apparatus of this invention is best understood by referring to FIG. 3 through 5 of the drawings. In these Figures, the welt tensioning apparatus of this invention is generally designated by the numeral 20. The welt tensioning apparatus is associated with a standard, industrial sewing machine 22 having a sewing needle 24. A base 26 supports the sewing machine and the welt tensioning apparatus.

A welt guide arm 28 is provided which has a remote end 30 and a free end 32. A fastener 34 (FIG. 4) secures the remote end 30 of the welt guide arm 28 to adjustable brackets 36 and 38. The bracket 36 is adjustably mounted by fasteners 4040 to the bracket 38. The bracket 38 is adjustably mounted to the base 26 by fasteners 42-42. In such a manner, the free end 32 of the welt guide arm 28 is positionable in any desired position with respect to the sewing needle 24 of the sewing machine 22 for the purposes of directing the welt l 1 thereto.

The free end 32 of the welt guide arm 28 has an opening 44 formed therein. The opening 44, in this case, has a keyhole shaped cross section. The keyhole shape is selected in this case because the welt 11 has a keyhole shaped cross section. The opening 44 is dimensioned so as to closely confine the welt therein.

A welt tension lever 46 is provided which has a remote end 48 and a free end 50. The free end is formed so as. to have a half key shaped portion 52 thereon which engages the top surface of the welt 11 when passing thereunder. The welt tension lever 46 is pivotably secured to the welt guide arm 28 for movement with respect thereto by structure now to be described. Intermediate the ends of the welt tension lever 46 is formed a depending portion 54 having an opening 56 therethrough (FIG. 5). Intermediate the ends of the welt guide arm 28 is formed a pair of upstanding projections 58-58 having openings 60-60 therethrough. When the openings 56 and 60 in the lever and the arm, respectively, are aligned, a pivot pin 62 (FIG. 4) is inserted to secure the two elements together. A small spring 64 is provided between the free ends of the lever and the arm in order to bias these elements to a normal position with respect to each other.

When the welt tension lever 46 is secured to the welt guide arm 28, the half key-shaped portion 52 on the free end 50 of the lever is in juxtaposition with the opening 44 in the free end 32 of the welt guide arm.

. Movement of the free end of the lever with respect to the free end of the arm particularly in a down direction as viewed in FIG. 4, forces a slight misalignment of the welt 11 as it passes through the opening 44 and then under the half key-shaped portion of the lever. This misalignment causes a drag on the welt 11 and results in a tensioning of the welt during its deliverance and passage under the needle 24 of the sewing machine 22. The amount of misalignment, of course, controls the amount of tension of the welt.

An air cylinder 66 is provided which contain a piston (not shown) and an operation lever 68 extending therefrom. The air cylinder is attached by means of an adjustable bracket 70 (FIG. 3) to the sewing machine 22. The free end of the operating lever 68 is secured to the remote end 48 of the welt tension lever 46. Movement of the piston within the air cylinder causes the operating lever to pivot the welt tension lever 46 about the pivot pin 62 so that the free end 50 and the half key-shaped portion 52 formed thereon assume different positions with respect to the opening 44 in the free end 32 of the welt guide arm 28. As previously explained, this change of position results in the application of different drags or tensions on the welt l 1. I

An air line 72 is connected through an air regulator 74 to an air supply 76. The other end of the air line 72 is coupled to the air cylinder 66. An adjustment knob 78 is functional with the air regulator 74 to permit adjustment of the air pressure in the air line to any desired degree. The air pressure on the air line side of the re gulator is indicated by an air gauge 80. Normally in the sewing of a welt for an automotive seat covering, an air pressure in the range of 15 to 60 pounds per square inch is required in order to permit adjustment of the operating lever 68 of the air cylinder 66 to different positions which result in different amounts of tension being placed on the welt during the sewing operation. When a controlled or regulated amount of air pressure is supplied to the air cylinder, the operating lever 68 thereof is set in a precise position to apply a set amount of force on the free end of the welt tension lever. If the cross sectional size of the welt 11 changes, the same controlled amount of force will be applied by the free end of the welt tension lever to the welt because a readjustment of the position of the lever will take place.

If more or less tension is desired on the lever, the adjustment knob 78 of the air regulator 74 is moved to increase or decrease the air pressure from the air supply 76 to the air line 72. This adjustment may be read on the air gauge 80. The change in the pressure in the air line 72 causes a repositioning of the free end of the welt tension lever whereby a controlled amount of force is applied, as desired, to the welt passing thereunder.

There has been disclosed herein a welt tensioning apparatus which is economical to construct and to employ. The apparatus permits a controlled amount of tension to be applied during a welt sewing operation to the welt being fed to a sewing needle. The apparatus also permits and easy adjustment of the actual tension applied on the welt to any one of a vast number of pressures indicative of selected tensions.

Many modifications of the welt tension apparatus disclosed in this specification will be obvious to those skilled in the art upon reading this specification. It is intended that all such modifications be included within the scope of the appended claims.

What I claim is:

1. Apparatus for controlling the tension applied to a welt being fed to a needle of a sewing machine which comprises:

' basemeans for supporting a sewing machine;

a welt guide arm having an opening therein at a free end thereof through which the welt is passed; mounting means for securing said welt guide arm to said base means in such a position that said free end of said arm is positioned in proximity to the needle of the sewing machine;

welt tension lever means pivotably secured to said welt guide arm for applying a pressure on the welt at a position in juxtaposition to said opening in said free end of said arm;

fluid pressure controlled force applying means coupled to said welt tension lever means for applying a force on said lever means to control the actual amount of pressure applied by said lever means on said welt; and

fluid pressure regulating means for varying the force plying means is a piston-cylinder device; wherein said piston supports an operating lever having a free end; and wherein said free end of said operating lever is coupled to said welt tension lever means.

3. The apparatus of claim 2 wherein: said pistoncylinder device is controlled by air pressure; and wherein said fluid pressure regulating means is an air regulator having an adjustable control means for controlling the pressure of the air delivered therefrom to said cylinder.

4. Apparatus for applying a controlled tension on a welt fed to a needle of a sewing machine which comprises:

a sewing machine with a sewing needle;

a base means for supporting said sewing machine;

a welt guide arm having a remote end and a free end;

said free end of said welt guide arm having an opening therein, said opening having the same general configuration as the cross sectional shape of the welt so that the welt may be passed therethrough in a close, confining relationship;

first mounting means for securing said remote end of said welt guide arm to said base means in such a position that said free end of said arm is in proximity to said needle of said sewing machine;

a welt tension lever having a free end and a remote end, said free end of said lever being shaped so as to be in general conformity with one surface of the welt;

second mounting means for pivotably securing an intermediate portion of said welt tension lever to said welt guide arm in such a position that said free end of said lever engages the welt at a position in juxtaposition to said opening in said free end of said welt guide arm, said free end of said lever applying tension on said welt by forcing a slight misalignment in the welt between its passage through said opening of said arm and its passage by said free end of said lever engaging the same;

fluid pressure controlled adjustment means coupled to said remote end of said welt tension lever for pivoting said lever about said second mounting means so that said free end of said lever assumes different positions with respect to said opening of said arm thereby to change the tension on said welt; and Y fluid pressure regulating means for varying the pressure applied to said adjustment means so that said last mentioned means pivots said welt tension lever to various positions so that said tension applied to the welt by said free end of said lever is controlled to a prescribed amount and the tension on said welt delivered to said needle of said sewing machine is substantially uniform over extended time intervals.

5. The apparatus of claim 4 wherein: said tension lever is mounted on an upper surface of said welt guide arm; and wherein said free end of said welt tension lever is shaped to conform with the upper surface of the welt.

6. The apparatus of claim 4 wherein: said fluid pressure regulating means is an adjustable air regulator; and wherein said adjustment means includes an air pressure controlled piston-cylinder device.

7. The apparatus of claim 4' wherein: said first mounting means includes adjustable bracket means for permitting adjustment of said welt guide arm with respect to said needle of said sewing machine; and wherein said second mounting means includes an upstanding projection on said welt guide arm, a depending portion on said welt tension lever, and a pivot pin.

8, Apparatus for applying a controlled tension to a welt having a keyhole shaped cross section being fed to a needle of a sewing machine, the apparatus also for permitting rapid adjustment of that tension to any desired level, which apparatus comprises:

a sewing machine with a sewing needle;

a base means for supporting said sewing machine;

a welt guide arm having a remote end and a free end;

said free end of said welt guide arm having an opening therein, said opening having a keyhole shaped cross section of the same general size as the keyhole shaped cross section of the welt so that the welt may pass therethrough in a close confining relationship;

first mounting means including an adjustable bracket for pivotably securing said remote end of said welt guide arm to said base means in such a manner that said free end of said arm is adjustably positionable in proximity to said needle of said sewing machine;

a welt tension lever having a free end and a remote end, said free end of said lever having a half keyhole shape so as to be engageable with an upper surface of the welt;

second mounting means including upstanding portions formed on an intermediate portion of said welt guide arm, a depending portion formed on an intermediate portion of said welt lever, and a pivot pin for pivotably interconnecting said two portions in such a position that said free end of said lever engages the welt at a position in juxtaposition to said opening in said free end of said welt guide arm, said free end of said lever applying a tension on said welt by forcing a slight misalignment in the welt between its passage through said opening of said guide arm and its passage under said free end of said lever engaging the same;

an air cylinder containing a piston with an operating lever extending therefrom, the free end of said operating lever being coupled to said remote end of said welt tension lever, movement of said piston within said air cylinder causing said operating lever to pivot said welt tension lever about said applied to the welt by said lree end of said tension lever is controlled to a prescribed amount and the tension on said welt delivered to said needle of said second mounting means so that said free end of said lever assumes different positions with respect to said opening in said free end of said welt guide arm thereby to change the tension on the welt;

means for supplying air under pressure to said air cylinder; and

an air pressure regulator coupled to said air supplying means, said air pressure regulator being adjustable to vary the pressure applied to said air sewing machine is substantially uniform over extended time intervals.

9. The apparatus of claim 8 wherein: a small spring is included between said welt guide arm and said welt tension lever near the free ends thereof to bias said lever arm towards a normal position where no tension is ap- 10 plied to the welt passing under the free end thereof.

10. The apparatus of claim 8 wherein: a pressure gauge is coupled with said air pressure regulator so that cylinder to cause operation of said operating arm Pressure of said Pressure pp to Said air to various positions thereby to pivot said welt tencylmder may be measured sion lever to various positions so that said pressure 

1. Apparatus for controlling the tension applied to a welt being fed to a needle of a sewing machine which comprises: base means for supporting a sewing machine; a welt guide arm having an opening therein at a free end thereof through which the welt is passed; mounting means for securing said welt guide arm to said base means in such a position that said free end of said arm is positioned in proximity to the needle of the sewing machine; welt tension lever means pivotably secured to said welt guide arm for applying a pressure on the welt at a position in juxtaposition to said opening in said free end of said arm; fluid pressure controlled force applying means coupled to said welt tension lever means for applying a force on said lever means to control the actual amount of pressure applied by said lever means on said welt; and fluid pressure regulating means for varying the force applied by said fluid pressure controlled force applying means on said welt tension lever so that said pressure applied to said welt by said lever means is controlled to a prescribed amount and the tension on the welt delivered to the needle of the sewing machine is substantially uniform over extended time intervals.
 2. The apparatus of claim 1 wherein: said force applying means is a piston-cylinder device; wherein said piston supports an operating lever having a free end; and wherein said free end of said operating lever is coupled to said welt tension lever means.
 2. The apparatus of claim 1 wherein: said force applying means is a piston-cylinder device; wherein said piston supports an operating lever having a free end; and wherein said free end of said operating lever is coupled to said welt tension lever means.
 3. The apparatus of claim 2 wherein: said piston-cylinder device is controlled by air pressure; and wherein said fluid pressure regulating means is an air regulator having an adjustable control means for controlling the pressure of the air delivered therefrom to said cylinder.
 4. Apparatus for applying a controlled tension on A welt fed to a needle of a sewing machine which comprises: a sewing machine with a sewing needle; a base means for supporting said sewing machine; a welt guide arm having a remote end and a free end; said free end of said welt guide arm having an opening therein, said opening having the same general configuration as the cross sectional shape of the welt so that the welt may be passed therethrough in a close, confining relationship; first mounting means for securing said remote end of said welt guide arm to said base means in such a position that said free end of said arm is in proximity to said needle of said sewing machine; a welt tension lever having a free end and a remote end, said free end of said lever being shaped so as to be in general conformity with one surface of the welt; second mounting means for pivotably securing an intermediate portion of said welt tension lever to said welt guide arm in such a position that said free end of said lever engages the welt at a position in juxtaposition to said opening in said free end of said welt guide arm, said free end of said lever applying tension on said welt by forcing a slight misalignment in the welt between its passage through said opening of said arm and its passage by said free end of said lever engaging the same; fluid pressure controlled adjustment means coupled to said remote end of said welt tension lever for pivoting said lever about said second mounting means so that said free end of said lever assumes different positions with respect to said opening of said arm thereby to change the tension on said welt; and fluid pressure regulating means for varying the pressure applied to said adjustment means so that said last mentioned means pivots said welt tension lever to various positions so that said tension applied to the welt by said free end of said lever is controlled to a prescribed amount and the tension on said welt delivered to said needle of said sewing machine is substantially uniform over extended time intervals.
 5. The apparatus of claim 4 wherein: said tension lever is mounted on an upper surface of said welt guide arm; and wherein said free end of said welt tension lever is shaped to conform with the upper surface of the welt.
 6. The apparatus of claim 4 wherein: said fluid pressure regulating means is an adjustable air regulator; and wherein said adjustment means includes an air pressure controlled piston-cylinder device.
 7. The apparatus of claim 4 wherein: said first mounting means includes adjustable bracket means for permitting adjustment of said welt guide arm with respect to said needle of said sewing machine; and wherein said second mounting means includes an upstanding projection on said welt guide arm, a depending portion on said welt tension lever, and a pivot pin.
 8. Apparatus for applying a controlled tension to a welt having a keyhole shaped cross section being fed to a needle of a sewing machine, the apparatus also for permitting rapid adjustment of that tension to any desired level, which apparatus comprises: a sewing machine with a sewing needle; a base means for supporting said sewing machine; a welt guide arm having a remote end and a free end; said free end of said welt guide arm having an opening therein, said opening having a keyhole shaped cross section of the same general size as the keyhole shaped cross section of the welt so that the welt may pass therethrough in a close confining relationship; first mounting means including an adjustable bracket for pivotably securing said remote end of said welt guide arm to said base means in such a manner that said free end of said arm is adjustably positionable in proximity to said needle of said sewing machine; a welt tension lever having a free end and a remote end, said free end of said lever having a half keyhole shape so as to be engageable with an upper surface of the welt; second mounting means including upstanding portions formed on an Intermediate portion of said welt guide arm, a depending portion formed on an intermediate portion of said welt lever, and a pivot pin for pivotably interconnecting said two portions in such a position that said free end of said lever engages the welt at a position in juxtaposition to said opening in said free end of said welt guide arm, said free end of said lever applying a tension on said welt by forcing a slight misalignment in the welt between its passage through said opening of said guide arm and its passage under said free end of said lever engaging the same; an air cylinder containing a piston with an operating lever extending therefrom, the free end of said operating lever being coupled to said remote end of said welt tension lever, movement of said piston within said air cylinder causing said operating lever to pivot said welt tension lever about said second mounting means so that said free end of said lever assumes different positions with respect to said opening in said free end of said welt guide arm thereby to change the tension on the welt; means for supplying air under pressure to said air cylinder; and an air pressure regulator coupled to said air supplying means, said air pressure regulator being adjustable to vary the pressure applied to said air cylinder to cause operation of said operating arm to various positions thereby to pivot said welt tension lever to various positions so that said pressure applied to the welt by said free end of said tension lever is controlled to a prescribed amount and the tension on said welt delivered to said needle of said sewing machine is substantially uniform over extended time intervals.
 9. The apparatus of claim 8 wherein: a small spring is included between said welt guide arm and said welt tension lever near the free ends thereof to bias said lever arm towards a normal position where no tension is applied to the welt passing under the free end thereof.
 10. The apparatus of claim 8 wherein: a pressure gauge is coupled with said air pressure regulator so that the pressure of said air pressure supplied to said air cylinder may be measured. 